package com.shoppingwebsite.servlet;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.shoppingwebsite.domain.Result;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.List;
import java.util.Random;

/**
 * 验证码
 */
@WebServlet("/checkCode/*")
public class CheckCodeServlet extends BaseServlet {
    /**
     *    查找一张验证码
     */
    public void find(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //服务器通知浏览器不要缓存8
        response.setHeader("pragma", "no-cache");
        response.setHeader("cache-control", "no-cache");
        response.setHeader("expires", "0");

        //在内存中创建一个长80，宽30的图片，默认黑色背景
        //参数一：长
        //参数二：宽
        //参数三：颜色
        int width = 80;
        int height = 30;
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        //获取画笔
        Graphics g = image.getGraphics();
        //设置画笔颜色为灰色
        g.setColor(Color.GRAY);
        //填充图片
        g.fillRect(0, 0, width, height);

        //产生4个随机验证码，12Ey
        String checkCode = getCheckCode();
        //将验证码放入HttpSession中
        request.getSession().setAttribute("CHECKCODE_SERVER", checkCode);

        //设置画笔颜色为黄色
        g.setColor(Color.YELLOW);
        //设置字体的小大
        g.setFont(new Font("黑体", Font.BOLD, 24));
        //向图片上写入验证码
        g.drawString(checkCode, 15, 25);

        //将内存中的图片输出到浏览器
        //参数一：图片对象
        //参数二：图片的格式，如PNG,JPG,GIF
        //参数三：图片输出到哪里去
        ImageIO.write(image, "PNG", response.getOutputStream());
    }

    /**
     *    对验证码进行验证
     */
    public void check(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //校验验证码
        String code = request.getParameter("code");
        //从session中获得验证码
        String checkcode_server = (String) request.getSession().getAttribute("CHECKCODE_SERVER");

        //比较
        Result info = new Result();
        if (checkcode_server == null || !code.equalsIgnoreCase(checkcode_server)) {
            //验证码错误
            info.setFlag(false);
            info.setInfo("验证码失败!");
        }else{
            //验证码正确
            info.setFlag(true);
            info.setInfo("验证码正确!");
        }

        System.out.println(info.getInfo());
        System.out.println(info.getFlag());

        //返回给客户端
        writeValue(info,response);
    }

        /**
         * 产生4位随机字符串
         */
    private String getCheckCode() {
        String base = "0123456789ABCDEFGabcdefg";
        int size = base.length();
        Random r = new Random();
        StringBuffer sb = new StringBuffer();
        for (int i = 1; i <= 4; i++) {
            //产生0到size-1的随机值
            int index = r.nextInt(size);
            //在base字符串中获取下标为index的字符
            char c = base.charAt(index);
            //将c放入到StringBuffer中去
            sb.append(c);
        }
        return sb.toString();
    }
}



